The present invention relates to electronic organs, and in particular, to electronic organs in which a portion of the data concerning depressed keys can be stored in a memory, on command, thereby permitting the player to use both hands elsewhere on the keyboard.
In many modern electronic organs, multiplexing techniques are employed for connecting at least a portion of the organ keyboard with the respective keyers. Such a system involves the scanning of the respective portion of the keyboard at a suitable scanning rate, say, 150 kilohertz, and the developing of a data stream by the multiplexer consisting of time displaced bits with signals corresponding to keys that were depressed at the time of the respective scan appearing in respective time slots of the data stream.
This data stream is supplied to a demultiplexer wherein the key-down signals in the stream are supplied to the input sides of latches for the corresponding latches, the outputs of which are connected to keyers for the respective tone signals. At the end of each such scan of the keys, the latches are updated by a pulse supplied by the multiplexer.
It is also known in such a system to provide detecting circuitry to detect the depression of a key in the multiplexed portion of the keyboard and to develop a signal in conformity therewith which will permit the flow of data to the demultiplexer. In all such systems, keys must be depressed to produce sounds except where automatic preset devices are employed for playing note patterns on command.
The present invention has as its primary objective the provision, in a multiplexed organ system, of a memory arrangement operable, upon command, to store in the demultiplexer the data corresponding to the keys which were depressed at the time of giving the aforesaid command.
When the portion of the keyboard normally played by the left hand is provided with the memory system, a player can depress the keys corresponding to a chord, and activate the memory system, and will then have both hands free to play elsewhere on the keyboard, as in the portion usually played only by the right hand. The arrangement thus adds substantial possibilities for the organ player.